Desires of the Blood
by jbluphin
Summary: John and Sherlock have something in common of which they are both unaware. They've both been holding back from starting a relationship with the other because of the one aspect of their lives they are *sure* they cannot share. Serial Killer AU.


**1. Discovery**

She was perfect.

Sherlock was off deducing the crime scene when John glanced out the window and noticed the tall blonde woman peering over the fence - she lived next door, and was clearly curious about the commotion in her neighbor's back yard. The neighborhood was near a major road, and the houses were far enough apart that noise didn't carry well between them. No one had heard the man screaming (and he surely had - John shivered at the thought as he eyed the mangled corpse before him); the murder hadn't been reported until a few days later, when the wife returned from her business trip and found her husband lying dead in their kitchen.

John smiled softly to himself: a true pleasure, that sound. Music to the ears... and it was so rare that he could indulge himself these days. He'd have to take special care.

* * *

She was perfect.

Sherlock took in the woman as Lestrade questioned her about her knowledge of her neighbors. The woman lived alone, talked rarely to her family, and worked mostly from home - she wouldn't be noticed missing for days, until her boyfriend - no, fiancé (even better) - stopped by, wondering why she hadn't returned his calls. He'd be the one to take the fall for it, of course, the obvious suspect: it would be almost _too_ easy. And so much more interesting than the current crime scene (Dull: a burglar, interrupted mid-way, who panicked as he tried to escape).

Sherlock didn't smile to himself, but his mind was spinning with delicious possibilities.

**2. Desire**

Falling in love with Sherlock Holmes was frighteningly easy - killing for him was just an occasional, unexpected bonus. If it wasn't for his own... little extracurricular hobby... John might have even pursued the matter. But a relationship with Sherlock _couldn't_ be a casual thing. And John was a bit of a romantic: he believed in honesty in a relationship. He couldn't hide such an important part of his life from his partner forever, especially someone as observant as the consulting detective. It was a miracle the man hadn't noticed his unusual habits already - if they ever became intimate, John was sure he'd be found out immediately. Besides, Sherlock wasn't even interested.

* * *

Of course, Sherlock knew John's regard for him went beyond that of mere friendship. How could he not? But he knew John's affection would only go so far. Attraction, yes, and admiration - but John was good man. He wouldn't overlook murder. After all, Sherlock had seen an example of John's treatment of serial killers. John would discover who Sherlock REALLY was, turn away in disgust, and turn him in. Sherlock was far better at concealing his own feelings on the matter. Imagining that look on John's face - the disappointment, the loathing - if he ever found out Sherlock's secret was enough for him to suppress his desires. The thought was almost enough to make him consider stopping his ways altogether. Almost.

**3. Needs**

John made a habit of coming back a little late from work when Sherlock didn't call for him; of running errands, or working beyond his hours, or even just going for a walk. He varied the routine. This made it easier for his little preparations to go unnoticed. He didn't indulge himself often; indeed, since moving in with Sherlock eight months ago, he'd only satisfied himself twice. The excitement of crime-solving with Sherlock not only cut into his usual routine, but made it less necessary - the rush of adrenaline and the sight of bodies and blood were a regular enough occurrence without orchestrating his own. But the restlessness still crept through him, slowly but surely, until he needed to take action on his own. After all, at a crime scene, he was only seeing the end result. It was a fine sight, to be sure, but nothing compared to creating it yourself. Nothing like carving up your victim and hearing them scream.

* * *

If someone had ever asked, Sherlock would have said he started because he was bored - but really, it would have been a lie. The first time it was simply due to curiosity. The criminals he chased were so _boring_, so _obvious_, it was amazing they thought they could get away with it at all. The process of murder seemed, in theory, simple enough that even an idiot should be able to do it without leaving much of a trace. But after solving crime after crime, he wondered if he was missing some unforeseen difficulty. So he decided to try it once himself, just to see. And to his delight, he found it an unexpected _challenge_ to create a crime scene that even _he_ couldn't deduce. He didn't do it often (and less, now that John was here), but every so often, when The Work became just a bit too unbearably slow, he would chose someone. He would find the perfect victim, the perfect scenario, the perfect alleged perpetrator, and set his scene.

**4. Revelation**

John hummed to himself as he examined the woman in front of him. It had been easy to talk himself into the house using the excuse of a broken down car and begging for the use of her phone. From there, a simple injection, just enough to knock the woman out for a few minutes until he could secure her on the floor with a few straps he had brought for that very purpose. Supplies were easy enough to come by, for a doctor. And getting away from Sherlock had been surprisingly easy, this time - that was usually the hardest part. But it had only been a week since he'd found the woman, and the detective had announced he was performing some time sensitive, all-night experiment at Bart's, and wouldn't be back until the next day.

She was just starting to wake up now - he couldn't wait to see the terror in her eyes.

* * *

It was just past dusk when Sherlock arrived to the house. As the shadows elongated, Sherlock slipped through the yard to the back door. He picked the lock easily, carefully leaving no trace - it would look as if the killer let themselves in with a key, later - a point towards the ultimate conviction of the fiancé. He readied the wrench he'd taken earlier from the fiancé's flat - one swift strike would render the woman unconscious, allowing him time to arrange the scene to his liking before he killed her. He had entered and examined the house earlier in the week and knew the layout exactly, and from observations knew she would likely be checking emails in the front room. The door led him into the kitchen, which was quiet. He crept softly towards the front room, and froze at the scene before him.

There, on the floor, was his chosen victim: bound, naked, whimpering. A gag was in her mouth, leather straps holding her wrists above her, and two more were holding her ankles fixed. She was bleeding slightly from several shallow cuts across her chest. And kneeling down beside her, smiling and enraptured, was Doctor John H. Watson, scalpel in hand.

Sherlock stared in shock - he must have made some sound, because suddenly, John looked up from where he was kneeling and froze in startlement and panic.

"Sherlock... What..." He cut himself off, and a look of something like anguished resignation crossed his face.

"Oh, God... I didn't want you to see me like this, Sherlock." His voice was rough and low, almost a whisper. "But if someone was going to catch me, I'm glad it was you. I won't resist." John dropped the scalpel, which fell with a soft thud onto the carpeted floor, and he stood up slowly. He put his hands together, towards the detective. "Do you want to cuff me? I wouldn't hurt you, but... I understand if you don't believe me right now."

Sherlock couldn't move, or speak. The woman between them was all but forgotten, for all that she was crying, muffled by the gag.

John continued, "But I have to know - how did you know what I was going to do tonight? When did you figure it out?" His voice almost cracked at the question.

The two men stared at each other for a long moment. Sherlock's mind was racing, pieces falling rapidly into place. John was a murderer; and more than that, Sherlock thought, glancing down at the bound figure between them: based on the evidence before him, John was a serial killer. His eyes took in the rest of the scene in a flash. A backpack lying open in the corner, a few straps hanging out of it. A jug of flame accelerant sitting beside the bag. A leather case, open next to John's bare feet, displaying a wide variety of knives and scalpels. And of course, John - wonderful, _fascinating_ John - standing in the middle of the room, his arms outstretched, quietly waiting to be arrested by his detective flatmate.

"I didn't." Sherlock spoke finally. "I didn't know."

John was silent, considering this, a question on his face.

Sherlock continued, "I came here for the same reason you did."

Startled out of his reverie, John finally took in Sherlock's appearance. He wasn't wearing his usual well fitted suits - instead, he was in black jeans and a dark long sleeved shirt. He had a compact bag over his shoulder, and he was holding a wrench in his gloved hands. He looked, of all things, like a thief in the night. A thief, or a murderer.

Comprehension dawned, and John slowly lowered his hands from where he had been holding them.

**5. Passion**

"Well," John glanced down, a smile slowly breaking out over his face. "Care to join me, then?"

Sherlock looked at the woman between them. She was tall and slender; her wide blue eyes watered with tears as she looked up at Sherlock, pleading silently for him to help her. He smiled, knelt beside her, and cupped her terrified face in his hands, before turning his face up at John.

"This isn't _quite_ how I planned on doing this, but..." he held out a hand expectantly, glancing at the case of knives. John knelt down in turn, picked up his case and examined it carefully.

"For you... this one, I think." John ran his finger over a slim knife, a dagger, contrasting the scalpel he'd chosen for himself. He carefully picked it up with both hands and held it out to Sherlock. Sherlock grasped the handle, felt it's weight in his hand. It felt right. Sturdy. It glinted silver under the lights of the room. John picked up his scalpel once again, and they looked at the woman between them.

John had begun working before he'd been interrupted by Sherlock, but only just. A few fresh, precise cuts were marked on her torso - tracing under the curve of her breasts and curving up around them, as if delineating them. Sherlock followed these lines with the flat of the blade, not cutting yet, just observing. He scraped the long edge of the knife down her torso to her belly, and she whimpered through the gag. He looked at John again, wondering where to begin. John smiled at him, put his hand on the woman's bare hip and pressed down, then put his scalpel at the crevice between hip and abdominal muscles and started a slice where the line of muscles separated. She began to scream again through the gag, thrashing and bucking wildly, but her limbs remained firmly fastened where they were tied. Sherlock held down her other hip, his eyes fastened to the small blade that was still slicing through muscle as the blood welled up from the wound. The cut was admirably steady, for all the woman thrashed, and Sherlock admired the doctor's skill. John finished his line, hands steady, and his eyes closed as he savored the sound of the woman's gagged wails.

With his hand firmly on her hip, Sherlock started to carve a matching line opposite to John's. The cut of the knife was subtly different from that of the scalpel, but the resulting line was still pleasing. At the top of her waist, instead of stopping where John had, he curled the line up and around her hip bone. He lifted, turning her onto her side, pressing down with more force and deepening the wound and carving into her buttocks, then allowed her to fall onto her stomach. Sherlock dragged the knife up her spine, just to the right of the vertebrae, causing specks of blood to appear. He considered a moment, then drew a similar line on the opposite side, digging the knife in deeper as he reached the small of her back, causing her to give another screech.

John laughed, and his scalpel danced between the slight grooves between her ribs, thin horizontal red lines criss-crossing the vertical ones that Sherlock had carved.

"Beautiful," he stated, admiring his work.

"Yes," replied Sherlock, looking at John. John kept his eyes fixed on their victim, drawing patterns on the woman's back. Sherlock contemplated his next step.

The woman's hair was long, halfway down her back, and a dark blonde colour. Sherlock drew his knife up and ran it up her neck, took hold of the hair in one hand, and in one swift motion sliced it all off at the nape of her neck. He held the resulting hunk of hair in his fist, then tossed it to the side, looking back down to where John was working.

John's doctoral inclinations were showing - he had continued to outline muscle groups and bone structures. Around her shoulder blades the contours almost resembled wings. Her back was a red mess: it was no longer a back at all, so much as a cut of meat. The woman's cries were hoarse, now - her screams had faded to soft sobbing, even as Sherlock idly made a few cuts into the back of her left thigh. It was the sound of hopelessness.

John turned, and smiled over the body at Sherlock. He pushed up on one of the shoulders, and Sherlock took that cue to help flip the woman over again. She emitted a cry of anguish as she fell onto her ruined back.

"Almost finished now - she'll be going into shock," stated John. He twitched the blade of his scalpel a few times over her body, deliberately nicking her major arteries. Femoral. Carotid. Brachial. She would die of blood loss soon - she was already shaking. John wiggled his toes and grinned, barefoot in the blood drenched carpet.

Sherlock watched John, hands red, eyes shining, scalpel dripping beads of blood. The man had never looked so alive, so enticing. Sherlock took the knife in his hand and pressed slightly, the tip poised just between where her ribs met at her sternum, not yet penetrating the skin. "May I...?" whispered Sherlock. John's eyes were hot as he nodded yes.

Sherlock angled his knife up between her ribs, smoothly sliding home into her heart. With a final shudder, the woman gasped and sputtered, laying still at last.

Sherlock's eyes locked with John's, over the body between them, his hands still on the knife.

And suddenly they were kissing, kissing, kissing and blood and tears were mingling on their lips and none of it was their own. Lips locked and eyes closed as their bloodied hands entangled and they were grasping at each others backs, ignoring the body between them, collapsing over it. Sherlock's shirt was the first to go, followed by John's trousers and they were rolling across the floor, desperate and wanting and far too long gone to care about such details as _evidence_. John clawed at Sherlock's jeans, forcing them down over his hips until they were grinding skin against skin, erection against erection, closer and closer.

Sherlock's back pressed into the bloodstained carpet, the weight of John pushing him down into the wet, as he instinctively arched his back to match thrust for thrust. John's lips were glued to Sherlock's collarbone, biting at the base of his neck, licking and sucking and gasping, while Sherlock scrambled desperately to remove John's shirt in order to access _more skin_. Sherlock gasped as John's blood slickened fingers found his cock, warm and wet and sure.

Sherlock took action, arching his neck to catch John's lips with his own. One lean leg snaked around John's body, pincering him between his thighs, as his fingers grasped John's back. And with one swift motion, suddenly Sherlock was on top, John beneath him, gazing up at Sherlock's sharpened grin. Pulse racing, he pressed another bloody kiss to John's lips, urging the other man's mouth open, exploring with his tongue. He ran a hand through John's hair, fingers stroking and pulling at the fine strands.

John growled at that, taking control once more, flipping them and pinning Sherlock against the floor. Sherlock moaned, his long fingers clutching at John's arse, squeezing, nails digging in. John nuzzled his nose into Sherlock's neck, teeth grazing that pale expanse of skin, before softly biting, tugging at his ear, pushing Sherlock utterly over the edge as John's fingers shifted in their grip on his cock. John came soon after, in a shuddering gasp, a warm, wet sensation spreading across Sherlock's hip.

They lay still, chests heaving, John's comforting weight upon Sherlock's body, for a few minutes before they finally broke apart. John rolled slowly off of Sherlock and onto his back, so that they were side by side. As they caught their breath, the room slowly came back into focus and they once again became aware of their surroundings. Sherlock turned onto his side to face John, taking everything in. His eyes were captured by a streak of red - almost a perfect handprint - which lay centred on John's tanned chest, and he gently placed his hand on top of it: a perfect match.

John's head turned towards Sherlock, eyes meeting once again, dark and serious. Sherlock opened his mouth, then closed it, uncertain what to say, what to do.

Suddenly, John burst into a fit of laughter, and Sherlock stared a moment before John continued, gasping, "We can't giggle, it's a crime scene!"

At the old joke, Sherlock started to chuckle, a grin spreading over his face, and at once everything seemed natural and right.

**6. Finish**

They looked at the scene around them - the room was splattered in blood, strewn with clothing, and had a mangled corpse in the centre, leaking heavily.

"Messy," commented John, rolling over, and propping himself on his elbows.  
"Yes, far more than usual for me, at least," Sherlock replied.  
"I like it messy," continued John, "but we should at least deal with the evidence. Can't have this lead back to us, now, can we?"

Sherlock gestured towards the corner where John had left the accelerant with his backpack. "I see you've got a way to deal with it, at least."

"It seemed the easiest. It's been a while for me, so I figured I might get a bit carried away. Well, I guess I did... but not in the way I expected." He grinned at Sherlock, and nodded at his bag, laying forgotten by the door to the kitchen. "Do you have anything that could help?"

"My plans lay in a different direction, I'm afraid - I have some materials which would implicate her fiancé in a crime of passion, though not quite to this extreme. We'll plant it anyway, but I doubt they'd believe this of him. He wouldn't be capable of making such surgical precision cuts, for one," he smiled at John. John grinned at the implied compliment, and replied with a cheeky wink,

"Then I suppose the culprit will forever remain a mystery."

They both reluctantly stood, stretching. They made quick work of it, after that. They gathered the most soiled materials and piled them on top of the body, pouring on plenty of accelerant. Sherlock made sure to give the carpet a good drenching as well - it needed to be the FIRST thing to burn, as they'd surely left plenty of DNA ground into it in their haste, their want, their need.

John fastidiously removed the straps he had so carefully secured earlier, then gathered and cleaned his knives and put them into Sherlock's bag, which was miraculously spared being bloodied. Once they were satisfied with the scene in front of them and Sherlock's bag was packed away with all the extras, John produced a large pack of wipes. They carefully sponged each other off - they were both covered in red. They used the entirety of the pack and still hadn't gotten everything; finally, Sherlock decided they had to risk it, and gave his hair a quick rinse in the kitchen sink, just to make sure all most visible blood was gone. John followed suit, then they both put on the spare clothes they had brought.

"We'll have to burn these as well, when we get home, after a shower," said Sherlock, gesturing down at his fresh clothing. John nodded in response.

And with that, Sherlock held a lighter to a firestarter and tossed it on the pile. Everything went into flames instantly, and they quickly ducked out into the kitchen and through back door before the fire could spread to other rooms.

They stood, watching the house burn for a minute or two before turning and walking away. Already they could hear sirens in the background. Sherlock twitched, slightly. He knew they had used less - much less - than his usual level of care, but it had all been too wonderful, too sudden. But fire would destroy the bulk of evidence against them, and without any other connection to the crime, he doubted anything would lead investigators their way. But still. John noticed his tension, and put his hand on Sherlock's shoulder as they walked.

"Next time, we'll do it your way," John smiled to Sherlock, radiating anticipation and satisfaction. And Sherlock smiled back - happy, truly happy and content, possibly for the first time in his life - at John.

He was perfect.


End file.
